Response Frame; Normal Response Frame; Error Response Frame - Omron E5CN Manual

SECTION 5 Modbus Communications Procedure

■ Response Frame

● Normal Response Frame
● Error Response Frame
Slave address
Function code
Error code
CRC-16
5-4
Slave Function
address code
1 1
CRC-16 calculation range
Slave Function Error
address code code
1 1 1
CRC-16 calculation range
The number specified in the command frame is entered as-is.
This is the unit number of the Unit returning the response.
This is the received function code with the hexadecimal value
of H'80 added to indicate that the response is an error
response.
Example: Received function code = H'03
Function code in response frame when an error occurred =
H'83
This code indicates the kind of error that occurred.
Cyclical Redundancy Check
This check code is calculated with the data from the slave
address to the end of the data.
The check code is 2-byte hexadecimal.
CRC-16
Data
2 bytes
CRC-16
2 bytes